F=60, s=60/2=30
(60-x)/(30-x)=4
60-x=120-4x
60+3x=120
3x=60
x=20  
s=30-x
s=30-20
s=10
So the boy was 10 years old when his father was four times his age.
        
             
        
        
        
Okay, here goes. Notice that since the line of reflection was the x-axis, the x-coordinate of each vertex stays the same and the y-coordinate of each vertex is the opposite of the original vertex, so in that case the answer is 4 or D.
        
             
        
        
        
Answer:x=-8
Step-by-step explanation:subtract 21 from both sides then simplify 31-21 to -8
 
        
             
        
        
        
Answer:
357
Step-by-step explanation:
5% of 340 is 17 add that to 340, the price of bicycle by itself and you get 357
 
        
             
        
        
        
Answer:
<em>P=760</em>
Step-by-step explanation:
Three of the coordinates of the square ABCD are A(-212,112) B(-212,-3) C(2,112). The image below shows the square is not ABCD but ABDC. In fact, this is not a square, as we'll prove later.
Note the x-coordinate of A and B are the same. It means this side is parallel to the y-axis. Also, the y-coordinate of A and C are the same, meaning this side is parallel to the x-axis. The missing point D should have the same x-coordinate as C and y-coordinate as B, i.e. D=(2,-3).
This shape has sides that are parallel to both axes.
To calculate the perimeter we find the length of two sides.
The distance from A to B is the difference between their y-axis:
w=112-(-3)=115
The distance from A to C is the difference between their x-axis:
l=2-(-212)=215
It's evident this is not a square but a rectangle. The perimeter is
P=2w+2l=330+430
P=760